Stinks how? fish smell or old rotting fish smell? The smell of poop or the smell of old stale water in need of a flush? Staying near the surface usually means (for fish) that there is either not enough oxygen in the water, which means you need to stir the water up (with a falling bit of water from the filter or by pumping bubbles into the water - both are used to aerate water). OR there is too much ammonia, nitrates, nitrites, etc. For both (to test to see if either is the problem) you can purge your tank. This requires filling a bucket with fresh water and letting it stand for at least 6 hours (to reach room temperature and to outgas chlorine and other chemicals added to tap water - if you have a well then 2 hours may be long enough). After the time above, then you remove about half the water in the tank usually by using a cup or something and pulling off a little bit of water at a time so as to not scare the fish to death. Then Stir the water you have in reserve vigorously enough to mix in air with the water but not so fast/hard as to slosh the water all over - give it about a two minute stir (more than enough to incorporate air into the water). Then SLOWLY add the fresh, room temperature, out gassed, oxygen enriched fresh water into the holding tank. Adding a little bit at a time slowly and gently until the bowl/tank/sink/toilet tank, whatever the fish calls home is full. Then sit back and observe and see what the fish does. IF s/he continues going to the surface with all of that fresh water and fresh air, then there may be other water issues or your old water is really bad. Some common Betta fish illnesses can be found here: http://www.bettatalk.com/betta_diseases.htm Read through the whole thing before jumping to a diagnoses. you can see your fish and you know what is normal for it and what is not normal. I say change the water first because water is usually the first area of a problem when it comes to fish. IF the semi-water purgedoes do the trick then it may desire to either change the filter and add a charcoal filter along with a biological component to filtration, or you may desire to get a large filter that is rated for a tank around 5 gallons more than your tank/bowl/pool/bathtub where ever the fish makes its home. (Much added information because I like you): ============================================ IF your fish is in a bowl, meaning without filtration, pumps and all of that, you may seriously desire to upgrade to a 5 gallon tank. 5 Gallon is large enough to stabilize and afford room for not only growth but for the wastes and offers a buffer of time for problems with water. I have found many, many tanks and tank accessories (pumps, filters, fish toys, gravel, etc) at yard sales. rule of thumb is to buy one then give it a 24-hour soak in a water bleach solution, 1 cup of bleach to each gallon of water. Any used accessories (filters (WITHOUT THE FILTERING PART), hoses, toys, gravel, fake plants, thermometers, etc) that will be in contact with the water that the fish will be in can also be placed in the tank for the soaking. I would advise setting up the tank for this soak outside. If you are fortunate enough to have power out doors, then setting up the filter, pumps, hoses, etc with the tank and letting them run for 24 hours with the bleach solution will clean them. After 24 hours empty and rinse, and rinse, and rinse - at least 5 times - if you ran the pump/filer/hoses run with fresh clean water for at least and hour after each rinse. DO NOT USE THE OLD USED filtration part, different filter systems have different filters, some are all combined into one (charcoal/bio/mesh) others come with separate types of filters set into the hardware. Not only will this sterilize and clean the tank of pathogens, it will also allow you to test to see if the tank or any of its components leak. If there is a leak in the glass there are sealants, if the pump leaks you need a new pump, if any of the tubes leak, they are easy to replace. After you have cleaned and rinsed, locate the tank to its permanent home (away from direct sunlight, a north facing window is ok, south facing without an awning is a bad idea) - fill and assemble all of the bits and pieces then run the pump and filter (WITHOUT THE FILTERING PART) for at least 6 hours (chlorine & Chemicals and to reach room temperature). Add what ever chemicals you use (Go to that site to find information on different chemicals for tanks). Move the fish and some water into a plastic bag - enough for him/her to move about trap air at the top and tie off the top. Gently place the bag in the new tank let it float for about an hour. After and hour remove the bag, open it and move the fish (NOT THE WATER) to the new tank.

It could be his swim baldder. Fish have a small air bladder that helps keep them afloat. Sometimes there are problems with it. This is info from the site that Athreal posted. I hope it helps. DISEASE: SWIM BLADDER DISORDER uGENERAL INFO: This is also a common betta problem. It is not contagious. It comes from overfeeding. It is especially common in very young bettas (30 to 60 days old) and can affect some Double Tail bettas when overfed or stressed.. uSYMPTOMS: Bettas with a swim bladder disorder will have difficulty swimming, because their swim bladder (located alongside the spine between the belly and the tail) is either too short (causing them to not be able to swim horizontally) or it is swollen (causing them to float on one side). Double Tail bettas, because they have a shorter body, are especially prone to the “floaters” problem. In the case of a short swim bladder, the bettas will not be able to maneuver and swimming becomes so difficult, they prefer to just lay at the bottom, sliding on their bellies, which is why they are called “belly sliders”. And they do look like a pathetic bunch, at that point. :) uTREATMENT: Bettas may recover on their own, but since overfeeding induces swimbladder disorders in most cases, the first thing to do is feed a lot less. Brine shrimp and too much of it is the biggest culprit, so if your bettas are bellysliding, stop the brine shrimp for a while and thereafter learn to have a more balanced diet, alternating brine shrimp with microworms or worms (depending on how old your bettas are). Do not kill a betta with a swimbladder disorder. It may recover on its own at any time, and is not suffering. Further more, the ailment is NOT contagious. To help the fish if it cannot eat, lower the water level. Adding some BettaZing to the water for a few weeks may not hurt either ;).